This invention relates to secondary lithium batteries. More particularly, the present invention relates to secondary or rechargeable lithium batteries using a lithium intercalation positive electrode (cathode) and a lithium intercalated negative electrode (anode).
Secondary lithium batteries using an intercalation compound as cathode and free lithium metal as anode have been studied intensively during the past decade due to their potential technological significance. Unfortunately, these studies have revealed that the inherent dangers associated with the use of free lithium preclude the commercial viability of such batteries. Efforts directed toward obviating this limitation have focused upon the concept of a "rocking chair battery" which substitutes another intercalation compound as the anode for the free lithium metal.
The output voltage of this rocking chair battery is defined by the difference in chemical potential of the two insertion compounds with respect to lithium metal. Accordingly, the cathode and anode must comprise intercalation compounds that can intercalate lithium at both high and low voltages, respectively.
Recently, workers in the art demonstrated the viability of this concept and indicated future commercialization of such cells in D, AA or coin-type batteries. These cells include either a LiCoO.sub.2 or LiNiO.sub.2 cathode, an electrolyte and a carbon anode. These rocking chair batteries are described as being superior to the available nickel-cadmium cells and do not require a stringent environment for fabrication since the lithium based cathode employed is stable in an ambient atmosphere, and the anode is not free lithium metal, but an intercalation compound used in its discharged state (without intercalated Li) that is stable in ambient atmosphere when the cells are assembled.